In the flip-chip assembly technique of the prior art, a pick-up head is used to assemble an un-encapsulated die onto a receiving substrate. For example, generally, in the electronics field, an un-encapsulated device that has already been completely formed can be referred to as “die”, and an encapsulated device can be referred to as “chip”. The un-encapsulated device can, for example, be a semiconductor device. For the clarity reason of description, in the context of this specification, the un-encapsulated flip device (un-encapsulated flip-chip) that has already been completely formed is referred as “flip-die”, and the encapsulated flip device can be referred to as “flip-chip”.
FIGS. 1A-1E show an example of assembling a die onto a receiving substrate by using a pick-up head.
As shown in FIG. 1A, a die 102 is picked-up by a pick-up head 101. The die 102 is of a flip-structure, in which the bumps thereof are located on one side. As shown in FIG. 1B, flux 104 is coated on the bumps 103 of the die 102. Then, as shown in FIG. 1C, the die 102 is placed on the receiving substrate 105. As shown in FIG. 1D, the bumps 102 are bonded onto the receiving substrate 105 through reflow. In FIG. 1D, underfill 107 is dispensed at the bottom of the die 102 by using a dispenser 106. As shown in FIG. 1E, the underfill 107 is cured, to finish the assembly of the die onto the receiving substrate.
The inventor of this invention has found that in the assembling method of the prior art, dies are picked-up and placed one by one. Thus, for a massive die array/matrix assembly (such as a micro-LED array for display), this approach is time-consuming. Generally, up to a few thousands of units, such as 2,000 units, can be assembled per hour by using a pick-up head. This assembly rate can in turn cause a cost issue.
Furthermore, the inventor of this invention has also found that the size of processed die is limited due to the capability of the pick-up and placement approach. For example, the size of dies that can be picked-up is equal to or larger than 150 μm.